Let's be honest.
Supporting a windows enviroment is easy and lowly paid. A quick call to an agency can bring a monkey over and he'll be able to support XP easily. Finding "good" linux staff is next to impossible.
We experimented 3 years ago with a trial run of 10 linux machines, and none of the IT support was happy supporting them. Even the only Linux enthuiast was having various configuration problems. The users also didn't like them in their Gnome desktop. Never tried KDE. Open Office was hated with venom by most users, especially using the spreadsheet.
I've yet to be convinced that linux is better value - I'd rather have 2 windows support staff for the price of a single linux support member - that's my view, I don't want to argue coz I wont be listening. na na nann nanannnannnaaa!